1. Field of the Invention
The present invention relates to both a method for controlling weeds and undergrowth in agricultural and industrial settings. The invention utilizes a spray of heated water for controlling the undesirable substances, and is particularly characterized by its application of a foam blanket downstream of the hot water spray, which serves to insulate the heated spray from ambient conditions, thereby increasing the efficacy of the spray in controlling undesirable weeds and undergrowth.
A first boom with nozzle openings, or a multitude of nozzles or openings, sprays hot water. Behind this first boom is a second boom that sprays a foam made up of various materials such as foam surfactant, polymers or oil emulsions so that the grass or weeds or vegetation that received the heated water does not cool off rapidly after being sprayed.
The foam, consisting of micro and macro bubbles, gives transient insulation characteristics similar to a flexible or stiff insulating canopy, as taught in U.S. Pat. No. 5,297,730.
This foam can be applied on weeds on the ground and also on standing row crops such as cotton for defoliation using hot water, or grape vines or other vines post pruning to heat kill dry fungus, bacteria or virus attached to the bark of these vines or living on the bark or stems of such vines.
2. Description of the Prior Art
Within the agricultural industry, various methods are known and recognized as being effective for controlling the growth of weeds and other undesirable substances. Many such methods involve the application of aqueous solutions of treatment chemicals onto the undesirable substances. Over the past years, as we have become more aware of our environment and the delicate balances that must be maintained in order to preserve a healthy environment, much care and concern have arisen over the utilization of toxic chemicals for weed and undergrowth control as well as for insect control. One merely has to read the labels of numerous commercially-available insecticides and herbicides to appreciate the caution which must be exercised in their proper use.
Utilization of herbicides and insecticides not only subjects the user to personal danger, but also may damage desirable crops if the treatment materials are not applied properly. Furthermore, accumulations of treatment materials in the soil and in water sources are now recognized as further dangers to the environmental balance.
In recognition of the dangers attendant to the use of herbicides and pesticides, manufacturers of such products maintain elaborate and expensive testing facilities. Both local and national governments also expend large sums of money and resources for the purpose of determining and monitoring safe and effective dose rates for such chemicals. In fact, most efforts for making the use of herbicides and insecticides safer to our environment involve efforts to formulate "safer" chemicals.
Nevertheless, prior patent literature does disclose at least one apparatus for eliminating undesirable vegetation growth which is relatively safe to the environment. U.S. Pat. No. 213,255 to Simpson discloses an apparatus which uses steam and/or hot water to kill vegetation on railroad beds. According to the disclosure of that patent, the application of steam and/or hot water provided by the steam locomotive engine is efficacious for killing vegetation which might seek to grow along the tracks and railway beds.
Other prior art devices such as, for example, U.S. Pat. No. 3,242,098, to Andrews, are also known in the prior art. However, the Andrews patent discloses an apparatus for generating a vapor or fog for purposes of concealment, for controlling atmospheric temperature, for disseminating insecticide or other materials into the outside atmosphere or into confined spaces, etc. A vehicle-mounted spray apparatus is disclosed in U.S. Pat. No. 4,817,870, to Dalton. However, the device of the Dalton patent is primarily concerned with spraying materials onto a road or highway. U.S. Pat. No. 3,986,670, to Syveson discloses a hand held thermal electric fogging device for dispensing a fog, or cloud, of insecticide. Other similar devices are also known in the art, and virtually all such devices that involve heating the material before spraying apply sufficient heat and pressure so that the material is dispensed as a fog. It is clear that the use of such vapors or fogs would be quite inefficient in that they would clearly be subject to drift onto plants which should not be treated and to significant dispersion into the atmosphere because of the gas-like nature of the fog. Furthermore, if active ingredient chemicals are included in such fogged sprays, hazardous conditions for both the operator and the surrounding environment may be created because of the wide dispersion of the fogged material.
It is, therefore, clear that there is a great need in the art for a new apparatus and method for controlling undesirable vegetation growth and insect infestation in a manner which would not result in the addition of new and increased levels of chemical poisons to our environment.